I do not know if that is true, but one of my teachers (for whom hair care was a priority) told me many years ago that it is better for the hair to be washed in a tub of water, than under running shower water. Water per my teacher needs to be changed several times, but having the hair fully submerged in water with shampoo is better than pouring water on it. I do not know what it was that made basically giving the hair a bath better than sprinkling it with water. I can ask. I think that the idea is that you first have the shampoo dissolve in the water fully and then have the shampoo solution coat the strands of hair evenly. When you put shampoo on one spot and work up a later from it, it is not as even as the tub method - some strands will be better coated than others. At least that is the only explanation that seems to make sense.